Nucleic acid hybridization assays are used as a tool for the detection and identification of a target genetic material such as DNA or RNA. Such detection and identification ca be for a specific DNA or RNA sequence or specific gene or a point mutation or deletion of a DNA or RNA sequence or gene. A number of techniques exist to carry out such assays. (see Methods In Enzymology, Vol. 68, R. Wu (Ed) pp. 379-469, 1979; and Dunn, A. R., and Sambrook, J., Methods In Enzymology, vol. 65; Part 1, pp. 468-478, 1980). One of the most w . used procedures is called the Southern blot filter hybridization method (Southern, E., J. Mol. Biol. 98, 503, 1975). This procedure is usually used to identify a particular DNA fragment separated from a mixture of DNA fragments by electrophoresis. The procedure is generally carried out by isolating a sample of DNA from some microorganism. The isolated DNA is subjected to a restriction endonuclease digestion and electrophoresed on a gel (agarose, acrylamide, etc.). When the gel containing the separated DNA fragments is put in contact (blotted with a nitrocellulose filter sheet or diazotized paper, etc.), the fragments are transferred and become bound to the nitocellulose sheet. The gel-transfer nitrocellulose sheet containing the DNA fragments is then heated to denature the DNA. At this point the sheet is treated with a solution containing a denatured labeled DNA probe and hybridization is allowed to take place. The unhybridized labeled DNA probe is then washed away. The label of the DNA probe is then detected.
It is known to carry out a homogeneous hybridization assay based upon non-radiative energy transfer. This hybridization assay system utilizes a chemiluminescent catalyst and an absorber/emitter moiety. The system involves the use of two polynucleotide reagent strands in such a way that the hybridization assays carried out are in a homogeneous fashion. This means that the target polynucleotide sequence can be detected and identified in solution without the need to carry out any immobilization procedures. The method comprises contacting the target genetic material, under hybridization conditions, with first and second single stranded polynucleotide reagent segments which are complementary to substantially mutually exclusive portions of the target single stranded polynucleotide. The first reagent segment has a chemiluminescent catalyst and the second reagent segment has an absorber/emitter moiety positioned such that, upon hybridization with the target single stranded polynucleotide, the chemiluminescent catalyst and absorber/emitter moiety are close enough in proximity to permit non-radiative energy transfer. The single stranded polynucleotide sample is then contacted with chemiluminescent reagents effective for causing light emission in the presence of the chemiluminescent catalyst. The quantity of light emitted by the absorber/emitter moiety is then measured by an appropriate instrument which thereby indicates the presence of the sample single stranded polynucleotide. This method is disclosed in European Patent Application Publication No. 0 070 685, published Jan. 26, 1983.